Separation of ethylbenzene from xylenes by extractive distillation

Abstract

Ethylbenzene is separated from xylene(s) by extractive distillation employing at least one copper(I) salt of a hydrocarbonsulfonic acid as extractant(s).

That which is claimed is: 
     
       1. A process for separating ethylbenzene from at least one xylene selected from the group consisting of ortho-xylene, meta-xylene and para-xylene contained in a feed, said process consisting essentially of subjecting said feed to extractive distillation and employing an extractant consisting essentially of at least one dissolved copper(I) salt of a hydrocarbonsulfonic acid; wherein said process produces (i) an overhead product which contains a larger volume percentage of ethylbenzene and a smaller volume percentage of said at least one xylene than said feed, and (ii) a bottoms product which contains said extractant and a larger volume percentage of said at least one xylene and a smaller volume percentage of ethylbenzene than said feed.   
     
     
       2. The process in accordance with claim 1, wherein the content of ethylbenzene in said feed is about 5-95 weight-% and the content of said at least one xylene in said feed is about 5-95 weight-%. 
     
     
       3. The process in accordance with claim 1, wherein the weight ratio of said extractant to said feed is in the range of about 0.02:1 to about 10:1. 
     
     
       4. The process in accordance with claim 3, wherein said weight ratio is in the range of about 0.1:1 to about 2:1. 
     
     
       5. The process in accordance with claim 1, further consisting essentially of the step of at least partially separating said at least one xylene from said extractant contained in said bottoms product. 
     
     
       6. The process in accordance with claim 5, further consisting essentially of the step of recycling said extractant. 
     
     
       7. The process in accordance with claim 1, wherein said at least one copper(I) salt of a hydrocarbonsulfonic acid is at least one copper(I) salt of an alkanesulfonic acid containing 4-20 carbon atoms per molecule. 
     
     
       8. The process in accordance with claim 7, wherein said alkane sulfonic acid is selected from the group consisting of n-butanesulfonic acid, 2-ethyl-1-hexanesulfonic acid, 2-methylnonanesulfonic acid, dodecanesulfonic acid, 2-ethyl-5-n-octyldecanesulfonic acid and n-eicosanesulfonic acid. 
     
     
       9. The process in accordance with claim 1, wherein said at least one copper(I) salt of a hydrocarbonsulfonic acid is at least on copper(I) salt of an aromatic sulfonic acid containing 6-22 carbon atoms per molecule. 
     
     
       10. The process in accordance with claim 9, wherein said at least one copper(I) salt of an aromatic sulfonic acid is dissolved in an aromatic hydrocarbon solvent so as to form a solution. 
     
     
       11. A process in accordance with claim 10, wherein the solution of said at least one copper(I) salt of an aromatic sulfonic acid in said aromatic hydrocarbon solvent has a concentration of about 0.05-2 mole/l. 
     
     
       12. A process in accordance with claim 11, wherein said at least one copper(I) salt of an aromatic sulfonic acid is copper(I) p-dodecylbenzenesulfonate. 
     
     
       13. The process in accordance with claim 12, wherein said copper(I) p-dodecylbenzenesulfonate is dissolved in xylene solvent. 
     
     
       14. The process in accordance with claim 9, wherein said aromatic sulfonic acid is benzenesulfonic acid. 
     
     
       15. The process in accordance with claim 9, wherein said aromatic sulfonic acid is at least one alkylbenzenesulfonic acid wherein the alkyl member contains 1 to 10 carbon atoms. 
     
     
       16. The process in accordance with claim 9, wherein said aromatic sulfonic acid is naphthalenesulfonic acid. 
     
     
       17. A process in accordance with claim 1, wherein the reflux ratio in said extractive distillation is in the range of about 0.1:1 to about 100:1. 
     
     
       18. The process in accordance with claim 1, wherein said feed consists essentially of ethylbenzene and said at least one xylene.